Abstract 15927: Glutaredoxin-1 Regulation of Interleukin-33 Induction in Macrophages
Glutaredoxin-1 (Glrx) is a cytosolic enzyme that removes glutathione (GSH) adducts from S-glutathiolated proteins. S-glutathiolation inhibits translocation or DNA binding of transcription factors including NFκB. The objective was to identify Glrx regulation of genes related to macrophage inflammatory phenotype. We analyzed gene profiles following challenge with the endotoxin, LPS, in mouse peritoneal macrophages (PM) from Glrx knockout (KO) and wild type (WT) mice by high-throughput 96 chip quantitative RT-PCR. The gene most highly induced (> 2,000 fold) by LPS (100 ng/mL) was IL-33, a cytokine associated with the alternatively activated M2 phenotype and with anti-atherosclerotic activity. IL-33 induction was markedly suppressed (90%) in Glrx KO PM (n=3, P<0.01). Other M2 genes, arginase-1 and IL-10, were also significantly inhibited in Glrx KO MP. In contrast, the M1 classically-activated genes, e.g. TNFα, were not inhibited by Glrx KO. Expression of the IL-33 receptor, ST2L, was significantly higher in Glrx KO MP suggesting reciprocal regulation of IL-33 and ST2L. Knockdown of Glrx with siRNA (Glrx KD) in RAW264.7 macrophage line resulted in attenuated IL-33 induction by LPS at mRNA and protein (ELISA) levels compared to control RNA. LPS-induced IL-33 was also attenuated while ST2L was upregulated in bone marrow derived macrophages (BMM) from Glrx KO compared to WT, despite comparable CD68 expression demonstrating that macrophage maturation was not affected by Glrx KO. We used RAW264.7 with Glrx KD to study mechanisms of regulation of IL-33 expression. The NFκB inhibitor, JSH23, inhibited LPS-induced IL-33 expression. LPS-induced IκBα degradation was also inhibited by Glrx KD. The proteasome inhibitor, MG132, inhibited IL-33 induction by LPS. Taken together, we showed that the LPS induction of IL-33 mRNA and protein in mouse macrophages was inhibited by depletion of endogenous Glrx. Inactivation of NFκB including proteasome dysfunction may be responsible for the IL-33 suppression. In conclusion, Glrx may be essential for the alternatively activated M2 response in macrophages through regulation of IL-33 and M2 genes, which could protect against inflammatory responses in macrophage-related diseases including atherosclerosis.
- © 2011 by American Heart Association, Inc.